This invention relates to an apparatus and method for transporting sheet paper, and more particularly to a sheet paper transportation apparatus and method using a piezoelectric device as a source of drive force.
Conventional sheet paper transportation mechanism used in the office automation (OA) equipment or the like is based on the feed roller which is driven by a stepping motor or the like through gears or a belt.
However, the simplification of the sheet paper transportation mechanism is requested as the OA equipment becomes compact. As means of accomplishing this requirement, developments of sheet paper transportation mechanisms which directly feed sheet paper by use of a piezoelectric device are under way. Refer to the NE report in publication "Nikkei Electronics", No. 446, pp. 74-75, published on May 2, 1988.
Although it is indispensable for a sheet paper transportation mechanism to provide a stable feed speed and feed value, a sheet paper transportation mechanism using a piezoelectric device, which bases the drive force on the friction between the vibrating actuator and the vibrated sheet paper when coming in contact with each other, creates a difference of feed speed depending on the gap between the vibrating member and the sheet paper the pressure acting on these members, and the properties (thickness, stiffness, etc.) of the sheet paper.